Research Interests

control theory, IoT, fluid power

Degrees

• PhD in control theory and mechanical engineering, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2022
• MS in control theory and mechanical engineering, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2017
• BS in control theory and mechanical engineering, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2015

Publications

1. J. Benić, J. Budja, Annotations About Croatian Areal-Diachronic Corpus Building, Čakavska rič : polugodišnjak za proučavanje čakavske riječi 51/1-2 (2024), 181-192
   Abstract

   The paper is about the areal-diachronic corpus of the Croatian language. Special attention is given to the data from the corpora of old texts (before the standardisation of Croatian), which would give a complete overview of and insight into the development of the language. The paper also describes the areal-diachronic sub-corpus consisting of works from the Makarska coast.
2. M. Krznar, D. Pavković, J. Benić, D. Brezak, M. Cipek, Hybrid Electrical-Internal Combustion Engine Power Supply for Multirotors: Feasibility Analysis and Case Study, Journal of sustainable development of energy, water and environment systems 12/2 (2024)
   Abstract

   Multirotors have proven their significance in fields like aerial imaging, surveying, and inspection. However, their effectiveness is hindered by limited flight autonomy due to the low energy density of standard lithium polymer batteries and high power demand. This necessitates frequent recharging, limiting prolonged operational capabilities. In response, our study introduces a methodology to assess the feasibility of a hybrid internal combustion engine and electric generator set as an alternative power source for multirotors. We investigate three theoretical multirotor designs tailored for mid-to-heavy load capacities (15 – 35 kg max take-off mass) and evaluate both pure battery and hybrid power as vehicle energy sources. Our findings indicate that hybrid power significantly enhances endurance, enabling extended flight times and wider range coverage. This extended aerial presence achieved with the hybrid system's superior endurance over traditional batteries significantly enhances multirotor capabilities, enabling innovative applications and expanded use cases.
3. J. Benić, D. Brezak, Ž. Šitum, D. Kolar, D. Lisjak, Detailed experimental comparison of energy efficiency between proportional and direct driven hydraulic system, Results in engineering 18 (2023)
   Abstract

   This paper investigates the energy efficiency of a Direct Driven Hydraulic (DDH) system and a proportional electrohydraulic system. A detailed analysis of their energy efficiency is carried out based on experimental results obtained in laboratory conditions using a fully loaded cylinder and sine wave reference trajectory. To ensure fairness in the testing process, the same cylinder with the same initial conditions is used for both systems. The cylinder velocity is estimated online using a novel algebraic differentiator approach based on measured cylinder position. The power of each component is calculated from the obtained measurements, and the energy efficiency of the system is given, along with the losses for each component. Based on the obtained results, it is concluded that the efficiency of the DDH system with a fully loaded cylinder is 28%, while that of the proportional electrohydraulic system is 4%. The significantly higher energy efficiency of the DDH system is attributed to its use of a power-on-demand approach, in contrast to the proportional electrohydraulic system.
4. J. Benić, A. Penđer, J. Kasać, T. Stipančić, Sugeno-Type Fuzzy Ontology PI Controller for Proportional Electrohydraulic System, IFAC-PapersOnLine 56/2 (2023)
   Abstract

   In this paper, an ontology representation of the Sougeno-type PI Fuzzy Logic Controller (FLC) is presented. The proposed controller is an extension of the Fuzzy Ontology Controller (FOC), where the new fuzzy annotations relevant to Sougeno-type fuzzy control are added to the ontology. The design of the fuzzy ontology is carried out in Protégé and it is hosted on a remote server in the Virtuoso database. Simulation results for the proportional electrohydraulic system are presented and compared to the PI and the SMC controller. The simulation results show that the proposed concept works, and achieves similar results to the PI controller. Experimental results are carried out on a proportional electrohydraulic system. Results show good tracking capabilities despite slow network communication between the server and experimental setup.
5. D. Kolar, D. Lisjak, M. Curman, J. Benić, Identification of Inability States of Rotating Machinery Subsystems Using Industrial IoT and Convolutional Neural Network - Initial Research, Tehnički glasnik 17/2 (2023), 279-285
   Abstract

   Rotating parts can be found in almost all operational equipment in the industry and are of great importance for proper operation. However, reliability theory explains that every industrial system can change its state when failure happens. Predictive maintenance as one of the latest maintenance strategy emerged from the Maintenance 4.0 concept. Nowadays, this concept can include Industrial Internet of Things (IIoT) devices to connect industrial assets thus enable data collection and analysis that can help make better decisions about maintenance activity. Robust data acquisition system is a prerequisite for any modern predictive maintenance task as it provides necessary data for further analysis and health assessment of the industry asset. Fault diagnosis is an important task in the maintenance of industrial rotating subsystems, considering that early state change diagnosis and fault identification can prevent system failure. Vibration analysis in theory and practice is considered a correct technique for early detection of state changes and failure diagnostics of rotating subsystems. The identified technical state should be considered in a context of the ability and different inability states. Therefore, early different inability states identification is the next step in the rotary machinery diagnostics procedure. Most of the existing techniques for fault diagnosis of rotating subsystems that use vibrations involve the step of extracting features from the raw signal. Considering that the features that describe the behavior of the rotary subsystem can differ significantly depending on the type of equipment, such an approach usually requires an expert in the field of signal processing and rotary subsystems who can define the necessary features. Recently, the emergence of machine deep learning and its application in maintenance promises to provide highly efficient fault diagnostics while simultaneously reducing the need for expert knowledge and human labour. This paper presents authors aim to use self-developed IIoT system built as an IIoT accelerometer as the edge device, web API and database with convolutional neural network as deep learning-based data-driven fault diagnosis to detect and identify different inability states of rotating subsystems. Large dataset for two different rotational speed is collected using IIOT system and multiple convolutional neural network models are trained and tested to examine possibility of using IIOT for inability state prediction.

6. J. Benić, M. Krznar, T. Stipančić, Ž. Šitum, A new concept of a fuzzy ontology controller for a temperature regulation, Iranian Journal of Fuzzy Systems 19/4 (2022), 125-136
   Abstract

   In this paper, a new concept of the fuzzy logic controller is presented. The proposed concept is called fuzzy ontology controller and it's based on an ontology description of the Fuzzy Logic Controller (FLC). In this concept, the SPARQL query sent to the ontology replaced the fuzzification process, fuzzy interface, and rules of the fuzzy controller while defuzzification is done on an obtained response. Fuzzy ontology is designed with Prot'{;e};g'{;e}; and hosted in the Virtuoso database on a remote server. Simulation results obtained with the proposed fuzzy ontology controller are compared to ones obtained with the classical fuzzy logic controller. Both controllers obtained the same simulation results due to the same membership function and defuzzification process. The results showed that this concept can be used as a part of some IoT solution within the vision of Industry 4.0. Also, results confirmed that the ontology-based controller works properly and gives the same output as FLC. The experiment is carried out on a heat exchange process controlled with a PLC. Modbus TCP protocol is used for communication between the server PC and a PLC. Experimental results show that only slow processes are controllable for now due to slow communication between PLC and server and the time needed for execution of SPARQL queries.
7. D. Pavković, M. Cipek, M. Krznar, J. Benić, A Retrofitting Control System Design Suitable for Deep Borehole Drilling Using Legacy Draw-Works Mechanical Brake Hardware, Energy conversion and management 260 (2022)
   Abstract

   Deep drilling operations are typically needed when producing deep wells for hydrocarbon exploitation or geothermal energy applications. Since a notable portion of existing deep drilling rigs are still fielding manually operated draw-works (hoist) drum mechanical brake actuators, their usage puts notable constraints on the quality of borehole production and corresponding production rates. By retrofitting such mature drilling rigs with a suitable brake actuator servo mechanism, completely automatic drilling operation can be facilitated, thus also achieving borehole production efficiency improvements and meeting the increasingly stringent requirements on drilling control system performance. To this end, this paper presents the development of an automatic drilling control system based on an electrical servoactuator of the draw-works mechanical brake, with the control system arranged in the so-called cascade control system structure, and an automatic tuning procedure having been devised as well. Its robustness has been tested by means of root locus plots and simulation analysis of dominant closed- loop dynamics effects. The proposed control system has been verified by means of simulations first, which has been followed by a thorough experimental verification on an actual deep drilling rig retrofitted with electrical servodrive based- actuator of the winch drum mechanical brake. Field results have indicated that the proposed control system can maintain the drill-bit normal force within 10% (+/-) of the target value during normal operation, with penetration rate variations typically being two to three times smaller compared to the case of human operator controlling the drilling process.
8. L. Koren, T. Stipančić, A. Ričko, J. Benić, Context-Driven Method in Realization of Optimized Human-Robot Interaction, Tehnički glasnik 16/3 (2022), 320-327
   Abstract

   Perceptual uncertainty and environmental volatility are among the most enduring challenges in robotic research today. Contemporary robotic systems are usually designed to work in specific and controlled domains where a total number of variables is defined. Traditional solutions therefore often result in over-constrained interaction spaces or rigid system architectures where any unexpected change can result in system failure. The focus of this work is set on achieving a constant adaptation of the system to changes through interaction. A computational mechanism based on the entropy reduction method is integrated along with the three- component control model. This model is seen as a context-to-data interpreter used to provide context-aware reasoning to the technical system. The mechanism is using a decrease in interaction uncertainties when proofs are provided to the system. In this way, the robot can choose the right interaction strategy that resolves reasoning ambiguities most efficiently.
9. J. Benić, J. Karlušić, Ž. Šitum, M. Cipek, D. Pavković, Direct Driven Hydraulic System for Skidders, Energies 15/7 (2022)
   Abstract

   This paper investigates potential uses of a novel direct driven electro-hydraulic systems for articulated forestry tractors (skidders), due to these systems having notably higher energy efficiencies compared to classical electro-hydraulic systems that are currently being used in skidders for steering, lifting the front and the rear plate, as well as for operating the double-drum winch. A detailed analysis of the skidder rear plate mechanism is carried out, and static force profiles of hydraulic cylinders are obtained for the rear plate based on mechanism dynamics and measurement data from the literature. Thus, obtained results have been used to emulate the real-life force profiles in laboratory experiments featuring both the classical and the proposed direct driven hydraulic systems for the purpose of comparative analysis of their energy and fuel efficiency. These results are subsequently used to estimate the skidder fuel consumption and possible fuel savings over the entire vehicle life span for the realistic vehicle utilisation scenario. The main result is that fuel consumption can be reduced up to five times in the case of direct driven hydraulic system, thus effectively resulting in return of investment period of about four years in the case of skidder being retrofitted with direct driven hydraulic system.
10. J. Karlušić, M. Cipek, D. Pavković, Ž. Šitum, J. Benić, Efficiency comparison of different powertrain structures intended for a hybrid skidder by utilizing a novel cascade optimization algorithm, e-Prime, advances in electrical engineering, electronics and energy 2 (2022)
    Abstract

    Hybrid powertrain presents a viable solution for reducing fuel consumption through powertrain electrification while simultaneously being independent from the electric grid or a charging station. Due to the fact that articulated forestry tractors (skidders) belong to the class of forestry machinery which is intended for field use, this operating independence is of high importance. A simple backward-looking model of a series hybrid powertrain skidder is developed and presented in this paper. The model is then optimized over a number of previously-defined operating missions which include realistic track slopes and variable loads. The results are compared with the results of conventional and parallel hybrid powertrains proposed in previous works. Optimization results show that total fuel consumption obtainable with the proposed series configuration over the parallel one is slightly higher (the total efficiency of series structure is slightly lower) when compared to the parallel structure. Therefore parallel configuration can be considered as optimal soulution.
11. J. Benić, L. Filipić, A synchronic and diachronic computer corpus of Makarska littoral dialects (Croatia), Jazykovedný časopis 72/2 (2021), 488-501
    Abstract

    This paper presents a synchronic and diachronic computer corpus of Makarska littoral dialects. This corpus was created as part of the project to explore the ikavian neoštokavian dialects of the narrow coastal area in Croatian region of Dalmatia around the town of Makarska. The dialectological characteristics of the dialects studied are briefly presented first, followed by presentation of the digital system. The system is logically organized in first part as a corpus of literary texts created from 1729 to 1803 and digitally processed, and in the second part from the materials collected through dialectological questionnaires prepared and methodologically adapted as part of the creation of the Croatian Linguistic Atlas. Methods of collecting linguistic data, method of input into the digital form and methods and possibilities of data processing will be explained. Based on the input and search strategies within the system, the examples will prove the origin of the dialects of the Makarska littoral to be that of the ikavian neoštokavian dialect described in the dialectological literature. This computer-based principle of work is a novelty in Croatian dialectology which has not been digitally processed so far and offers a basis for future dialectological research. This platform can be used in order to shorten the time of data processing and to analyse them more systematically and more efficiently. So far, there has been no such digital repository for any Croatian speech. This project represents a thorough synchronic and diachronic study of one rounded language area.
12. M. Krznar, D. Pavković, M. Cipek, J. Benić, Modeling, Controller Design and Simulation Groundwork on Multirotor Unmanned Aerial Vehicle Hybrid Power Unit, Energies 14/21 (2021)
    Abstract

    This paper presents the results of modeling, control system design and simulation verification of a hybrid-electric drive topology suitable for power flow control within unmanned aerial vehicles (UAVs). The hybrid power system is based on the internal combustion engine (ICE) driving a brushless DC (BLDC) generator supplying the common DC bus used for power distribution within the aircraft. The overall control system features proportional-integral-derivative (PID) feedback control of the ICE rotational speed using a Luenberger estimator for engine-generator set rotational speed estimation. The BLDC generator active rectifier voltage and current are controlled by proportional-integral (PI) feedback controllers, augmented by estimator-based feed-forward load compensators. The overall control system design has been based on damping optimum criterion, which yields straightforward analytical expressions for controller and estimator parameters. The robustness to key process parameters variations is investigated by means of root-locus methodology, and the effectiveness of the proposed hybrid power unit control system is verified by means of comprehensive computer simulations.
13. J. Karlušić, M. Cipek, D. Pavković, Ž. Šitum, J. Benić, M. Šušnjar, Benefit Assessment of Skidder Power-train Hybridization utilizing a novel Cascade Optimization Algorithm, Sustainability 12 (2020)
    Abstract

    Over the last decade, off-road vehicles are being increasingly hybridized through power-train electrification in terms of additional electrical machine-based propulsion and battery energy storage, with the goal of achieving significant gains in fuel economy and reductions in greenhouse gases emissions. Since hybrid power-trains consist of two or more different energy sources and may be arranged in many different configurations, there are many open questions in their design and powertrain energy management control, which may have influence on the hybridized power-train purchase cost and efficiency. The paper presents a simple backward optimization models of conventional and hybrid cable skidder powertrain. The models are then used in control variables optimization over one forest path in order to find the minimum possible fuel consumption. The optimization results show that 15% fuel efficiency improvement in winching and skid trail driving can be achieved with the selected hybrid powertrain. With that improvement, main hybrid drive components can be paid off in 13 years and if achieved efficiency improvement can be carried throughout all skidder’s operations pay off time is reduced to 44 months.
14. J. Karlušić, M. Cipek, D. Pavković, J. Benić, Ž. Šitum, Z. Pandur, M. Šušnjar, Simulation Models of Skidder Conventional and Hybrid Drive, Forests 11/9 (2020)
    Abstract

    The paper presents a hypothetical conversion of a conventional cable skidder powertrain to its hybrid version. Simulations of skidder operation were made for two existing forest paths, based on the technical characteristics of the engine, transmission system and the characteristics of the winch. Fuel and time consumption were calculated per working cycle considering the operating conditions (slope, load mass). The model was then converted to a hybrid version by adding a battery energy storage system in parallel with the electrical power generator and by employing an energy management control strategy. The dimensions of the battery and the power generator were chosen based on the characteristics of the existing winch with the aim of completely taking over its operation. The management strategy was selected using the specific fuel consumption map. All simulations were repeated for the hybrid drive under the same operating conditions. The results show that fuel savings of around 13% can be achieved with the selected hybrid drive and steering strategy.
15. M. Orešković, J. Benić, M. Essert, A Step toward Machine Recognition of Complex Sentences, TEM Journal 7 (2018), 823-828
    Abstract

    This paper presents theoretical and technological background of a model for machine recognition of complex sentences. It is based on the Syntactic and Semantic Framework (SSF) which implements fundamental linguistic fields network resources and encyclopedias. It can be used to extract subject, predicate and object, as well as other sentence's parts (e.g. NP/VP/PP), and in some cases even semantic roles. In compound sentences the machine can easily recognize independent sentences, whereas in complex sentences the machine recognizes the main clause and the related subordinate clauses as well as sentence types (subject, object, predicate, etc.). Using stored patterns various theories can be tested.

1. T. Stipančić, L. Koren, D. Rosenberg, T. Harwood, J. Benić, PLEA: The Embodied Virtual Being, 26th International Conference on Human-Computer Interaction, Washington D.C., Sjedinjene Američke Države, 2024
   Abstract

   The emergence of Artificial Intelligence (AI) marks a significant milestone in innovations, particularly with the advent of Virtual Beings (VBs) and Mixed Reality. VBs have transitioned from rudimentary programmed characters to elaborate, interactive entities capable of sophisticated human engagement. Enhanced with emotional intelligence, adaptive learning, and context-sensitivity, VBs offer nuanced interactions within both digital and real-world settings. A key breakthrough in this field is the development of affective VBs, which possess the ability to comprehend and react to human emotions, challenging the traditional view of AI as emotionless and strictly logical. This evolution prompts a reexamination of AI's societal role and the dynamics of Human-Computer Interaction. This study focuses on the complexities of VBs, particularly through the implementation of a virtual being named PLEA, manifested in both worlds: the virtual and the physical one through a robotic head. It discusses the utility of such agents in various applications and employs ethnographic communication methodologies for data collection and analysis to unearth interaction patterns. Additionally, it examines human reactions to PLEA through a user-centered design approach, highlighting interactions based solely on facial expressions between PLEA and human participants. This investigation aims to lay the groundwork for developing multidisciplinary methods to collect, analyze, and abstract data from real-time interactions and feedback sessions, advancing the is course on AI's integration into human social environments
2. M. Krznar, D. Pavković, J. Benić, D. Brezak, M. Cipek, Feasibility of hybrid ICE-Electric power unit for heavy lift multi-rotor UAVs, 16th Conference on Sustainable Development of Energy, Water and Environment Systems, Dubrovnik, Hrvatska, 2023
   Abstract

   The utility of Unmanned Aerial Vehicles (UAVs) in various industries and applications, such as aerial photography, surveying, and inspection, is being demonstrated daily. However, the limited flight time of UAVs remains a major bottleneck, due to the relatively low energy density of lithium polymer batteries, which are commonly used as a conventional energy source. This limitation requires frequent recharging and prevents long-duration flights. To address this challenge, we propose a mathematical model that analyses the feasibility of using an internal combustion engine and electric generator set as an alternative power source for multirotor UAVs. We conduct a case study on three hypothetical multirotor configurations with propulsion systems suitable for medium to heavy loads, corresponding to maximum take-off masses of 15 – 35 kg. Our model compares the relative performance between pure battery power and hybrid power sources. Results show that a hybrid power unit can provide significantly more endurance than a conventional battery power unit, allowing the UAV to fly for longer periods and cover larger distances before needing to recharge. This is particularly important for applications that require extended flight times beyond the critical point, such as search and rescue missions or surveillance operations. With a hybrid power source, UAVs can achieve an unprecedented endurance performance above the critical point compared to conventional battery power units.
3. M. Cipek, D. Pavković, J. Benić, Ž. Šitum, Mud Pump Pressure Pulsation Control Systems, International Conference Fluid Power 2023, Maribor, Slovenija, 2023, 203-218
   Abstract

   Drilling fluid is circulated through the well-bore during drilling operations to transport cuttings from the bottom of the hole to the surface. Hydrostatic high-pressure mud pumps are typically used for this purpose. Triplex pumps, which comprise three pistons mechanically displaced by 120 degrees, are the most common type of mud pump. When more than one mud pump is connected to the common high-pressure line, very high pressure peaks can occur due to asynchronous pump strokes. These pressure peaks can damage high-pressure mud lines and pressure equipment, such as valves and gaskets. They can also undermine well-bore stability. This paper investigates the process of pulsation creation and proposes adequate pressure control systems for pulsations reduction. The proposed systems are based on the use of passive and active control elements.
4. A. Penđer, J. Kasać, D. Brezak, J. Benić, An Algebraic Approach to the Identification of Linear Continuous Systems Using Laguerre Networks, IEEE EUROCON 2023 - 20th International Conference on Smart Technologies, Torino, Italija, 2023, 319-324
   Abstract

   Sažetak This paper presents an algebraic approach to linear continuous system identification using Laguerre networks. The proposed approach provides an indirect calculation of the coefficients for the Laguerre expansion of the system's transfer function, based on the Laguerre representations of the system's input and output. The algorithm's computational complexity can be significantly reduced for two specific choices of the input excitation function. The algorithm convergence properties and computational complexity is compared with the classical gradient algorithms. Furthermore, an optimal LQR controller with a state observer is designed using the Laguerre representation of the unknown linear system. Simulation results on a coupled-mass system with unknown parameters and unknown system order demonstrate the effectiveness of the proposed system identification and control methods.
5. M. Šušnjar, Z. Pandur, M. Bačić, H. Nevečerel, M. Cipek, J. Benić, K. Lepoglavec, Development of hybrid drive of skidder, The 55th International Symposium on Forest Mechanization (FORMEC) and the 7th Forest Engineering Conference (FEC), Firenca, Italija, 2023
   Abstract

   The paper presents a conceptual innovation solution of a hybrid skidder. The innovation refers to a hybrid skidder with a diesel engine coupled with a separate electric motor with two clutches, which enables multi-mode work modes and the replacement of a winch drive based on a hydraulic drive with a drive based on an electric motor. During the work of winching the role of the pump drive is taken over by the electric motor, so that during such activities the diesel engine can be turned off or idling in order to save fuel. In addition to the listed components, a battery for energy storage has been added. For the development of the hybrid drive, it was a necessary prerequisite to precisely determine the skidder's energy consumption when timber skidding in different field conditions. For this purpose, it was necessary to perform field measurements on existing vehicles. When analyzing energy consumption for the purposes of modeling the drive of a hybrid skidder, the key values are extreme - maximum values. The future hybrid drive must satisfy the need for energy in all operating conditions, including the most demanding situations that may occur when the skidder is operating in extreme conditions. For this reason, long-term monitoring and measurement of energy consumption was necessary in order to observe extreme situations and measure the highest energy consumption per working day, work cycle and individual work operation. The research was carried out on 2 skidders Ecotrac 140 V under real working conditions. WIGO-E (Telematic Data collector) measuring equipment with integrated GPS system and fuel flow meter (accuracy in milliliters) is installed on both skidders. Data on fuel consumption, position and direction of skidder movement, winch activity, engine speed, drive motor torque, gas pedal position and temperature were collected by connecting the CANBUS bus from the vehicle's computer to the WIGO-E gateway. WIGO-E transmitted all data via GSM communication to Web platforms (Cloud). In doing so, the data collection frequency from the skidder was achieved in the range of 3 to 5 seconds. In addition to remote data collection, the amount of wood extracted during each work cycle was also recorded in the field. In total, measurement data were collected for 272 working days of skidders. The conceptual solution of the hybrid skidder drive is based on the measurement data bases collected from two Ecotrac 140 V skidders, mechanical drive parameters (engine speed characteristics, transmission ratios, etc.), hydraulic and electrical system schematics. Mathematical and simulation models of hybrid skidder drive components and computer algorithms for data processing were developed and the structure of the elements of the hybrid drive (electric motor, batteries, control unit) were determined and presented in the paper.
6. M. Cipek, J. Karlušić, D. Pavković, J. Benić, Ž. Šitum, Optimized Heavy-Duty Hybrid Powertrain Intended for a Future Articulated Forestry Tractor, 17th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES), Pafos, Cipar, 2022
   Abstract

   Forestry vehicles have been increasingly equipped with hybrid electric power-trains in order to provide significant gains in fuel economy, and also to facilitate reductions in greenhouse gases emissions. Due to the fact that hybrid power-trains consist of two or more different energy sources, many questions in terms of power-train components sizing and energy management control are opened, and all of them have influence on the power-train purchase cost and operating efficiency. Therefore, this paper propose an combined optimization approach of powertrain components size along with energy management rules. The hybrid skidder powertrain components are optimized by parametric optimization algorithm with the aim to minimize their size while maintain comparable traction characteristics as conventional forestry vehicle. Optimal control rules are also optimized by recently introduced cascade optimization algorithm with the aim to reduce powertrain fuel consumption. The obtained optimization results are verified by a comprehensive computer simulations, and are also used to gain insights about the possible advantages of optimized powertrain in terms of fuel consumption reduction and related CO2 emissions. The optimization results are also used to provide recommendations for design of a realistic (online) control strategy.
7. J. Benić, J. Kasać, Ž. Šitum, T. Stipančić, System Modeling and Control of 2DOF Robotic Manipulator based on Dual Quaternion Approach, The 2nd International Conference on Electrical, Computer and Energy Technologies (ICECET), Prag, Češka Republika, 2022
   Abstract

   In this paper, the dual quaternion approach is used for kinematic and dynamic modeling and control of robotic manipulator with two degrees of freedom. Elementary quaternion and dual quaternion operations used for obtaining kinematic and dynamic models are given. The Denavit-Hartenberg convention is used with dual quaternions for obtaining a forward kinematic model from which rotation and translation information is extracted. A dynamical model is obtained using Euler-Lagrange equations. The kinetic energy of each link is expressed with velocity dual quaternion calculated from the kinematic model, and with inertia tensor and diagonal mass matrix while potential energy is given as a function of the position dual quaternion. Based on the dynamical model, two control schemes are presented. The first one uses a PD controller for each link of the given manipulator, while the second one utilizes a dual quaternion approach for the set point problem. The proposed controllers are tested in simulation and the results are compared.
8. Ž. Šitum, J. Benić, D. Semren, M. Petanjak, Hydraulic Actuator Control Using Cartridge Valves, 13th International Fluid Power Conference, Aachen, Njemačka, 2022
   Abstract

   By using built-in or cartridge valves, it is possible to realize cheaper hydraulic systems, which need less space, have a short switching time and less fluid leakage, less time for assembly and installation, and give a better appearance of the hydraulic system, because they are usually installed in an aluminium block. The paper presents a laboratory setup of a hydraulic servo system using cartridge 2/2 valves to achieve precise positioning of the hydraulic cylinder, with the aim of clearly demonstrating the application of these valves in industrial plants, as well as their use in various mobile systems. The article describes the implementation of a control algorithm for the realization of manual and automatic mode of operation of the system and several ways to realize the precise movement of the hydraulic cylinder and simulation of the actuator load.
9. J. Karlušić, M. Cipek, D. Pavković, J. Benić, Ž. Šitum, Optimized Control Strategy of Hybrid Skidder based on Realistic Operating Cycles, 17th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES), Pafos, Cipar, 2022
   Abstract

   Increasing demands in terms of reducing the cost of running forestry machines along with the regulatory pressures for lower exhaust emissions encourages the usage of hybrid powertrains in field applications. Hybrid power-trains consist of two or more different energy sources, which leads to many open questions in terms of energy management control, which have significant influence on the power-train, efficiency, fuel consumption and consequently on the operating cost and emissions of greenhouse gasses. Therefore, this paper proposes the optimal energy management control strategy intended to be used in hybridized articulated forestry tractor, also known as skidder. The proposed control strategy is verified on the previously developed skidder model by a comprehensive simulations over realistically recorded field data. The simulation results are used to gain insights about the possible advantages of proposed optimal control strategy in terms of feasible reduction of fuel consumption and related CO2 emissions.
10. J. Karlušić, M. Cipek, J. Benić, D. Pavković, Ž. Šitum, M. Šušnjar, Comparison of Different Powertrain Structures Intended for a Hybrid Skidder, 16th Conference on Sustainable Development of Energy, Water and Environment Systems, Dubrovnik, Hrvatska, 2021
    Abstract

    Hybrid powertrain presents a viable solution for reducing fuel consumption achieved by a powertrain electrification while maintaining the independence from the electric grid or a charging station. Due to the fact that skidders belong to the class of forestry machinery which is intended for field use, this operating independence is very important. A simple backward-looking model of a series hybrid powertrain skidder is developed and presented in this paper. The model is then simulated over a number of previously-defined operating missions which include realistic track slopes and variable loads. The results are compared with the results of conventional and parallel hybrid powertrains proposed in previous works. Simulation results show that 17% fuel efficiency improvement is obtainable with the proposed series configuration over the conventional skidder in skid trail driving. Finally, the return of investment period of series hybrid and parallel-hybrid configurations are compared, and their respective advantages and disadvantages are listed and discussed.
11. J. Benić, Ž. Šitum, M. Cikoja, D. Pavković, J. Kasać, Comparison of Sliding Mode Controller for Classical and Direct Driven Electrohydraulic System, 17th Scandinavian International Conference on Fluid Power, Linköping, Švedska, 2021, 28-35
    Abstract

    In this paper, a novel energy-efficient Direct Driven Hydraulic (DDH) drive is made in parallel with a classical valve-controlled proportional electrohydraulic system. In the proposed concept asymmetrical hydraulic cylinder is controlled with two reversible pumps directly connected to a servo motor. Due to direct control of the oil flow, such system provides higher energy efficiency in comparison to a valve-controlled hydraulic system. The experimental setup is designed with the possibility of easy switching between both systems, which enables an exact comparison of the experimental results. Sliding Mode Controller (SMC) is designed for the DDH system and also for the classical proportional electro-hydraulic system. A comparison study of two systems is done based on the experimental results obtained with the SMC while reference results are obtained with a widely used PID controller. Parameters for the PID controller are obtained with the Ziegler-Nichols method. The same parameters are used for both controllers in all test cases. The performance and energy efficiency of the proposed system is evaluated through a step and sine wave reference signal with different payloads varying from 0 to 200 kg with 20 kg increments. Additionally, system performance is evaluated based on six parameters calculated from the system response while energy efficiency is calculated based on input and output powers of the systems.
12. J. Benić, A. Vico, L. Vučetić, Ž. Šitum, IoT based WEB application concept for monitoring and control of fluid power systems, International conference Fluid Power 2021, Maribor, Slovenija, 2021, 316-325
    Abstract

    This paper presents a novel concept of the WEB application for monitoring and control of fluid power systems. The proposed concept is based on the internet of things principles. WEB application is built on the Web2py framework which uses Python as the programming language. The client-side of the proposed application is based on the responsive open source AdminLTE dashboard. On the server-side Python is used for executing SQL queries sent to the database and for continuous data logging. The ModbusTCP protocol is used as the communication protocol between the server and systems. The application is tested on two experimental setups. The first one uses an industrial PLC and the second one is an Arduino PLC as a control device. Finally, experimental results are presented and a conclusion is given.
13. J. Benić, J. Karlušić, Ž. Šitum, M. Cipek, D. Pavković, Potential Use of Novel Efficient Direct Driven Electro-Hydraulic System for Skidders, 16th Conference on Sustainable Development of Energy, Water and Environment Systems, Dubrovnik, Hrvatska, 2021
    Abstract

    Nowadays there are increasing demands in terms of reducing the cost of running forestry machines along with the regulatory pressures for lower exhaust emissions to improve the ecological indices and reduction of acoustic noise in order to comply with increasingly more stringent industry ergonomic guidelines. Therefore, the producers of forestry equipment are increasingly interested to make such heavy machinery more efficient, which can already be seen with the emergence of certain hybrid and electric powertrain-based forestry vehicles. However, many tools and accessories used by these heavy vehicles are still powered by hydraulics systems. For example, articulated forestry tractor known as skidder uses hydraulic steering, hydraulic lifting for front pushing plate or rear protection plate, and also uses a hydraulic double-drum winch. Having this in mind, this paper investigates the possible use of direct driven electro-hydraulic system instead of the classical one in order to increase the skidder’s operating efficiency. Both the classical and direct driven electro-hydraulic systems are modeled, simulated and experimentally verified for the purpose of comparative analysis of their efficiency. Experiments are carried out under laboratory conditions and experimental results are obtained both for the unloaded cylinder and different payloads. The obtained simulation results are used to gain insights about the possible advantages of the directly driven electro-hydraulic system.
14. F. Plavac, D. Pavković, M. Trstenjak, M. Cipek, J. Benić, D. Lisjak, Speed Control of a Series DC Drive for Drilling Applications with Vibration Damping Torque Feedback Loop, International Scientific Conference MMA 2021, Novi Sad, Srbija, 2021, 185-188
    Abstract

    The paper presents the speed control system design and simulation verification of a petroleum drilling system aimed at effective suppression of drill-string torsional vibrations in legacy drilling drives featuring mature series-wound direct-current motor drive technology. The vibration suppression system is based on the external damping feedback loop using a straightforward low-pass filter-based drill-string torque estimator and a reference correction term in the motor speed target path, with the motor speed feedback control system featuring a proportional-integral controller tuned for stiff disturbance rejection. The control system design is based on the damping optimum criterion, which results in straightforward analytical expressions for controller parameters. The effectiveness of the proposed control strategy is verified by means of comprehensive simulations.
15. D. Pavković, M. Cipek, Ž. Šitum, J. Benić, M. Šušnjar, Hybrid Power-trains for Sustainable Forestry - A Review, 4th South East Europe Conference on Sustainable Development of Energy, Water and Environment Systems, Sarajevo, Bosna i Hercegovina, 2020
    Abstract

    Nowadays there are increasing demands in terms of reducing the cost of running forestry machines along with the regulatory pressures for lower exhaust emissions to improve the ecological indices and reduction of acoustic noise in order to better comply with industry ergonomic guidelines. Therefore, the producers of forestry equipment are increasingly interested in electrification of heavy machinery, which can already be seen as appearance of the certain hybrid and electric forestry vehicles. The hybrid power-train apparently offers a favourable solution that can meet the above requirements for the propulsion of articulated forestry tractors, also known as skidders, due to the possibility of using a lower-power diesel engine, along with an additional energy storage system (e.g. battery) and driveline power source (i.e. electric motor). This allows the considered hybrid power-train configuration to operate with higher overall energy efficiency and higher mechanical performance indices over the conventional (diesel engine-based) propulsion system, and notably extended autonomy compared to fully-electrified power-trains. Moreover, hybrid power-train requires a smaller battery with less energy then its purely electric counterpart, which results in lower power-train weight and total installation cost. The precise determination of the energy consumption of different types of forest vehicles working in different operating regimes and under different terrain conditions is necessary to select the proper power-train for a specific application. The future development of electrified forestry vehicles is also a very important research topic in the field of sustainable forestry engineering. Having this in mind, this paper presents a literature review on existing solutions for hybrid forestry vehicle propulsion.
16. J. Karlušić, M. Cipek, D. Pavković, Ž. Šitum, J. Benić, M. Šušnjar, Benefit Assessment of Skidder Power-train Hybridization, 4th South East Europe Conference on Sustainable Development of Energy, Water and Environment Systems, Sarajevo, Bosna i Hercegovina, 2020
    Abstract

    This paper presents a hypothetical conversion of a conventional articulated forestry tractor known as skidder to its hybrid counterpart by incorporating a battery energy storage system. Starting from the basic parameters of 84 kW diesel-powered skidder currently found in the national forestry company fleet, the quasi-static model of the skidder is derived and validated. The conventional skidder model is then converted to its hybrid counterpart by adding a battery energy storage system in parallel with the electrical power generator and an adequate energy management control strategy. The hybrid skidder power-train components are also appropriately re-sized in order to meet comparable traction force and power performance. Both the conventional and hybridized skidder models are then used for the purpose of comparative analysis of main vehicle characteristics for the off-road driving scenario, which includes realistic slope and terrain limitations. The obtained simulation results are used to gain insights about the possible advantages of the proposed conversion/drive-train hybridization in terms of feasible reduction of fuel consumption and related CO 2 emissions, while also considering additional hybridization costs and return of investment period.
17. J. Benić, Ž. Šitum, Position Controller for Direct Driven Electro- Hydraulic System, International Conference Fluid Power 2019, Maribor, Slovenija, 2019, 181-193
    Abstract

    In the past few years, decentralized hydraulics gain advantage over classical hydraulics due to lower energy consumption, lower pressure losses in pipelines and easy automatization. In this paper, Direct Driven Electro-Hydraulic (DDEH) drive is made in parallel with a classical proportional hydraulic system. In DDEH control method the valve is replaced with reversible pumps/motors which are directly controlled with a servo motor. Such systems combine best properties of both hydraulic and electric drives. Proposed experimental setup is designed for easy switching between both systems which allows exact comparison of obtained experimental results. The nonlinear models of both systems have been derived using PID controller and simulated in Matlab program. Finally, the conclusion regarding precise position control and system dynamics is given in detail.
18. Ž. Šitum, D. Žgela, J. Benić, Wireless Control of an Electro-Hydraulic Robotic Manipulator, 11th International Fluid Power Conference, Aachen, Njemačka, 2018, 387-395
    Abstract

    This paper deals with the design, practical realization and wireless control of a prototype of an electro-hydraulic robotic manipulator (EHROM) suitable for handling heavy weight objects in industrial environment. The EHROM has been designed in the Laboratory for Automation and Robotics at the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb. The prototype has been completely built in cooperation with two Croatian companies and is fully open to implementations of various control methods. The robotic manipulator has three-degrees-of- freedom (spherical or polar kinematic configuration) with a hydraulic gripper at the end of the mechanical structure. The manipulator uses a load sensing hydraulic system that provides superior controllability regardless of the load and also contributes to the energy efficiency. Originally the manipulator had no advanced way of being operated, other than the use of joystick or levers on the hydraulic valve block itself. The control system has been upgraded with an assembly suitable for wireless control of the manipulator using a mobile device on iOS platform. This multidisciplinary task involved skills in mechanical engineering, electronics and electrics, as well as computing. The paper focuses on the wireless control of the manipulator using a low-cost microcontroller and custom made controlling interface.
19. T. Žilić, M. Essert, J. Benić, I. Kuzmanović Ivičić, Universal M-Valued logic, 6th World Congress and School on Universal Logic, Vichy, Francuska, 2018, 485-489
    Abstract

    This paper based on M-theory wants to show the correlation of Cartesian product of elements of ordered set with a basic, multi-value logic. Using simple algorithms discovered by M. Sare in the natural laws of electrical networks, it is possible to construct logical tables, i.e. grids, for all logic functions of n variables.
20. J. Benić, N. Rajčić, Ž. Šitum, Precise force control for hydraulic and pneumatic press system, International Conference Fluid Power 2017, Maribor, Slovenija, 2017, 57-71
    Abstract

    This paper presents the force control methods for a pneumatic and a hydraulic press. Both systems have been made for educational purposes as well as for experimental testing and verification of different control techniques. The pneumatic press contains a proportional pressure valve which is used for pressure regulation in a cylinder chamber and has direct impact on controlled force. The proportional pressure regulator also allows an indirect calculation of the cylinder force by measuring the control pressure at the valve outlet, which is less precise than direct measurement of pressing force by using a force transducer. Arduino board was used as a controller for the pneumatic press and it can be programmed via Arduino hardware support for Matlab/Simulink program or via Arduino open-source platform. The control algorithm is implemented in the Matlab/Simulink environment, which allows executing the simulation program in external mode, similar to the Real-Time Workshop tool. The hydraulic press contains a servo-solenoid pressure-control valve for regulating the cylinder pressure. The pressing force can also be indirectly measured by a pressure transducer which is installed in the cylinder chamber. Similar to the case of the pneumatic press, more precise measurement of the pressing force can be achieved with a force transducer. The control algorithm has been implemented on a real-time hardware board by using the Real-Time Workshop tool for generating the C code and building an executive program. Experimental tests have shown that electrically actuated control components supported by the appropriate measuring devices and computer programs make it possible to improve the characteristics of the hydraulic and pneumatic systems required in modern industrial plants.
21. M. Orešković, J. Benić, M. Essert, The Network Integrator of Croatian Lexicographical Resources, XVII EURALEX International Congress, Tbilisi, Georgia, 2016, 267-273
    Abstract

    In this paper we describe an online application which connects various Croatian lexicographical sources (the standard dictionary, professional terminology, and encyclopedias) into a new network framework, which solves the problems of the currently available network solutions and offers new features. Although developed for the formation and processing of the professional terminology of technical sciences (primarily engineering), this framework is easily extensible to all other science areas (humanities, medicine, architecture, etc.). From a word formation standpoint, this framework provides an automatic generation of a temporary dictionary of a given text (entered or taken from the web), comparison of and updating a permanent dictionary with a temporary one (detection of neologisms), an automatic display (standard, professional and encyclopedic) of definitions of the words from the main dictionary or external (network) sources of a given text. From the point of view of processing, the framework enables a classic text analysis (frequency, concordances, statistics), converting the collected data (e.g. technical words) to the linked open data (LOD), and storing it into the Virtuoso triplestore repository. On this data, a variety of professional ontologies for viewing and searching can be developed.

1. Z. Dabčević, J. Benić, Ž. Šitum, Web controlled pneumatic press, Ventil 27/2 (2021), 96-103
   Abstract

   The article describes a web controlled pneumatic press as an example of a system designed to demonstrate the control of pneumatic devices via the Global Area Network (GAN). System implementation is divided into several phases: (1) establishment of Internet protocol-based communication, (2) web application development, (3) reaction to events, analysis, and data display on the user's web page, (4) implementation of PID algorithm for force and position control of pneumatic press, (5) design and implementation of the human voice control system using artificial neural networks.

Professional Activities

Seminars and Talks

• 21.2.2019. “Upravljanje izravno pogonjenih elektrohidrauličkih sustava”, na seminaru Servohidraulika, Fakultet strojarstva i brodogradnje

Invited Lectures

• 8.6.2021. “Direct Driven Hydraulic and Internet of Things”, University of Maribor, faculty of Mechanical Engineering

Study Visits Abroad

• 21.3.2024. – 29.3.2024., M. O. Auezov South Kazakhstan State University, Kazakhstan